Tornado warnings topped off a stormy day in Granite State

Heavy storms caused flash flooding in parts of New Hampshire Monday and prompted a series of tornado warnings in northern Massachusetts, including one that extended into southeastern Hillsborough County.

The wild weather moved in by afternoon with rainfall rates of 1 to 2 inches an hour and intense thunderstorms that forecasters said had the potential to spawn tornadoes.

"The instability was causing storms to pop up and quickly die out. It's the same pattern that we've been having for the past week," said Alyssa Hammond, a meteorologist with the National Weather Service in Taunton, Mass.

Officials from the National Weather Service were surveying possible tornado damage in the area of Agawam and Springfield, Mass., while an EF1 tornado was confirmed near Windsor Locks, Conn.

The tornado threat surprised many people who were expecting only bouts of heavy rain. But as the thunderstorms formed, Hammond said they began to show rotation on radar.

"We were keeping an eye on it," she said.

The heaviest rain was concentrated on the southern part of the state, said James Brown, a meteorologist with the National Weather Service in Gray, Maine. The National Weather Service posted watches through this morning with 1 to 3 inches of rain expected to cause street flooding, washouts and rapid rises in some streams and rivers.